Question

public class Numbers2
{
    public static void main(String[] args)
    {
        int number;
        int numberTwo;
        int jordan;
        number = 5;
        numberTwo = 10;
        sum(number, numberTwo);
        difference (number, numberTwo);
        product (number, numberTwo);
        System.out.println(jordan);
    }
    public static void sum(int number, int numberTwo, int jordan)
    {
        System.out.print("The sum of the numbers is");
        System.out.println((number + numberTwo));
    }
    public static void difference(int number, int numberTwo, int jordan)
    {
        System.out.print(" The difference of the two numbers is");
            System.out.println((number - numberTwo));
    }
    public static void product(int number, int numberTwo, int jordan)
    {
        jordan = number * numberTwo;
        return jordan;
    }
}

错误是：

H:\Numbers2.java:10: sum(int,int,int) in Numbers2 cannot be applied to (int,int)
        sum(number, numberTwo);
        ^
H:\Numbers2.java:11: difference(int,int,int) in Numbers2 cannot be applied to (int,int)
        difference (number, numberTwo);
        ^
H:\Numbers2.java:12: product(int,int,int) in Numbers2 cannot be applied to (int,int)
        product (number, numberTwo);
        ^
H:\Numbers2.java:28: cannot return a value from method whose result type is void
        return jordan;
               ^
4 errors

Answer 1

更改您的代码...

public class Numbers2
{
public static void main(String[] args)
{
    int number;
    int numberTwo;
    int jordan;
    number = 5;
    numberTwo = 10;
    sum(number, numberTwo);
    difference (number, numberTwo);
    product (number, numberTwo);

}
public static int sum(int number, int numberTwo)
{
    System.out.print("The sum of the numbers is");
    System.out.println((number + numberTwo));
 return number + numberTwo;   // returns addition
}
public static intdifference(int number, int numberTwo)
{
    System.out.print(" The difference of the two numbers is");
        System.out.println((number - numberTwo));
 return number - numberTwo;  // returns the subtraction
}
public static int product(int number, int numberTwo)
{
    jordan = number * numberTwo;
    return jordan;   // returns the product
}
}

Answer 2

您似乎对如何在Java中定义和调用方法感到困惑。

我看到你的方法每个都有三个参数，但第三个参数是在你的方法中设置并返回的。定义方法时，在定义参数之前声明输出的type。在您的情况下，您当前将其定义为void。这告诉编译器您的方法不返回任何内容。在您的情况下，您想告诉它您的方法返回一个整数。这方面的一个例子如下：

public static int product(...

此外，当您调用方法时，您的调用必须与方法的签名匹配。这意味着您必须传入相同数量和类型的参数。在您的情况下，您的方法都被声明为输入三个int s，但是当您调用它们时，您只传入两个。

最后，我看到您传入一个名为jordan的参数，并尝试修改其值。默认情况下，java通过值＆＃34;传递对象＆＃34; （从技术上讲，它传递对象的引用，引用本身是＆＃34;值＆＃34;）。如果要实际修改参数的值，则必须在包装器对象中传递它。但是，在大多数情况下，您需要在方法内部创建一个新变量并返回该变量。一个例子如下：

// note the "int" keyword before the method name
public static int product(int number, int numberTwo)
{
    int jordan = number * numberTwo; // create a new variable to hold our response
    return jordan;   // returns the product

    // You can also just return the result of an operation:
    //return number * numberTwo;
}

错误是什么意思：[方法]不能应用于[参数]？

2 个答案: